In this morning's Boston Globe Gary Washburn wrote a story about the Celtics playing with an increased level of urgency since Rajon Rondo's injury. He shares some quotes from Doc Rivers, who gives a lot of credit to the return of Avery Bradley dramatically improving the team's defense. But Rivers also seems somewhat confused and pleasantly surprised by his squad's success without Rondo:

“I just think we’re playing better, for whatever reason. You have all those injuries, you usually go the other way. I just think our guys kind of came together and realized we don’t have a margin of error anymore."

The article has some quotes from Paul Pierce as well, who offers a bit of an explanation himself:

“Everybody was hearing the rumblings after the injuries. We were going to fall out the playoff race, this team can’t play with the elite teams in the Eastern Conference. Guys in the locker room are going to hear that and there’s a sense of pride about them and [it’s] making them better and making them compete.”

I believe the Captain and the Head Coach together have the answer: pride, and no margin for error. The explanation lies in the classic sports question "How good is your good?" With Rondo the Celtics knew what their "A" game could be (last season's Eastern Conference Finals and the victory over OKC in November come to mind), and they didn't feel the need to prove it on a nightly basis. But without him nobody knows how good Boston's good is, and they are continuously trying to show us. Wins like yesterday in Philly and Feb. 6th in Toronto are perfect examples. Previously the C's might lose road games against inferior opponents without worrying, because deep down they knew they'd beat them if really they had to. But now the Celtics (and the rest of the world) are unsure of their potential, so they're constantly attempting to raise the bar.